A 3-hydroxybutyric acid molecule has two functional groups, a hydroxyl group and a carboxyl group, which cause an integrated property of an alcohol and a carboxyl group, and make the 3-hydroxybutyric acid molecule an important pharmaceutical raw material and a pharmacological agent. (R)-3-hydroxybutyric acid is an R-isomer of the racemate of 3-hydroxybutyric acid, an optically active chiral compound, CAS No. 625-72-9. (R)-3-hydroxybutyric acid is a compound produced by metabolism of long-chain fatty acids in the liver in mammals. It is present as a major ketone body in plasma and peripheral tissues, and has excellent penetrating ability and rapid diffusion capability in human perivascular tissues, and can be used as a source of energy in most tissues of the body. In general, R-3-HB is present in the form of various salts. In addition to its nutritional function, (R)-3-hydroxybutyric acid has the function of treating many diseases, including: treating various diseases that benefit from increased levels of ketones (such as neurological disorders including epilepsy and myoclonus, and neurodegenerative diseases including Alzheimer's and dementia); reducing free radical damage (such as ischemia) by oxidizing coenzyme Q; enhancing metabolic efficiency (improvement of training efficiency and athletic performance, treatment of inadequate feeding, angina, myocardial infarction, etc.); treating diseases such as cancer, especially deseases related to brain cancer (such as astrocytoma); having good effects on glycemic disorders (such as type 1 diabetes, type 2 diabetes, hypoglycemia, ketosis, etc.); capable of being used to prevent osteopenia, osteoporosis, severe osteoporosis and related fractures. Based on these functions, (R)-3-hydroxybutyric acid and its salts can be used as food additives and medicines with great health and medicinal value.
The preparation of (R)-3-hydroxybutyric acid is mainly a chemical method and a microbial method. A disadvantage of the conventional chemical synthesis process is that the optical purity of the product is relatively low, i.e. the enantiomeric excess (ee value) is relatively low. Using the microbial fermentation method can directly obtain R-3-HB; or using microbial synthesis of poly R-3-HB followed by degradation of the polymer may also obtain R-3-HB. The product obtained from the microbiological method has a higher ee value. However, the complexity of the above processes and large investment in production lead to high cost and price of R-3-HB.